The present invention relates to contact-less electronic angular-position transmitters, in general.
In particular, the invention relates to a contact-less electronic angular-position transmitter for a mechanical setting member, in particular a weather vane, having a magnet which is turnable in proportion to the angle to be measured and having two sensor elements arranged at right angles to each other and adapted to be acted on by a magnetic field produced by the turnable magnet so as to produce one electric signal each, each signal being a measure of one of two field components which are oriented at right angles to each other.
Such angular-position transmitters are used for the remote indication of the position of a mechanical setting member in order to transmit the angular position by electric signals or to process or display it and/or use it for control and regulating systems. Such known angular position transmitters are preferably developed free of contact, i.e. an element which is turned in accordance with the setting member is not directly in contact with the sensor elements, so as to avoid basic disadvantages such as wear by friction and inaccurate adjustment of the turnable element.
In this connection, it is part of the prior art, particularly in the case of a wind measuring system, to couple a weather vane mechanically with a ferromagnetic toroidal magnet which is turnable within the field of influence of two Hall elements which are arranged at right angles to each other. As a result of the relatively slight sensitivity of the Hall elements as referred to the usable variable magnetic field, the turnable magnet must be turnable in the direct vicinity of the Hall elements.
The fact that the output signals of the Hall elements drift relatively substantially, for instance under the influence of temperature, is also disturbing. This results in the need for a high usable flux concentration, produced by the rotary magnet in the region of the Hall elements. Aside from this, an angular-position transmitter having Hall elements is rather expensive to produce for various reasons; the permanently magnetic toroidal magnet which is required because of the high flux concentration is relatively expensive. In addition, there are fabricating expenses resulting, for instance, from precise alignment of the two Hall elements at right angles to each other, which alignment must be continuously maintained.
The state of the art includes, furthermore, so-called synchros, one of which is provided on the transmitter side and one on the receiver side. The synchros have, within a stator, three coils which are 120.degree. apart and which are excited by alternating fields corresponding to the position of a rotor. The synchros on the transmitter side and the receiver side are connected to each other by three-wire lines (electric wave) and act in the manner that a rotor on the receiver side tracks the rotor on the transmitter side. With these synchros, to be sure, certain disadvantages of the Hall elements discussed above are avoided, but the cost of manufacture is even greater, particularly because of the synchro which is to be provided on the receiver side and which cannot be readily replaced by an electronic evaluation system. Such angular-position transmitters, therefore, are frequently only suitable if larger torques are to be produced on the receiver side.
The object of the present invention is, therefore, to provide a contact-less electronic angular-position transmitter which can be favorably assembled in mass production, which is characterized by a high degree of dependability and lack of sensitivity to the influences of temperature and moisture, and which is not critical with respect to the arrangement of the turnable magnet with regard to the sensor elements.